Q1: The phenomenon of strain-ageing is generally experienced with

ANS:B - low carbon steel.

The phenomenon of strain-ageing is typically experienced with low carbon steel. Explanation:

1. Strain-Ageing:
   • Strain-ageing is a phenomenon observed in certain metals, particularly steels, where the material undergoes changes in mechanical properties after plastic deformation (strain) followed by ageing at elevated temperatures.
   • It occurs when cold-worked or plastically deformed steel is subjected to an ageing treatment at moderate temperatures.
2. Low Carbon Steel:
   • Low carbon steels typically contain carbon content ranging from 0.05% to 0.30%.
   • These steels are commonly used in various applications due to their good weldability, formability, and moderate strength.
   • Low carbon steels are susceptible to strain-ageing when they are cold-worked or deformed plastically, followed by ageing at moderate temperatures.
3. Mechanism:
   • During cold-working or plastic deformation, dislocations are introduced into the crystal structure of the steel.
   • Subsequent ageing at moderate temperatures allows these dislocations to interact with carbon and other alloying elements, leading to changes in the material's mechanical properties.
   • Strain-ageing can result in an increase in strength and hardness, accompanied by a reduction in ductility and impact toughness.
4. Effect of Alloying Elements:
   • Alloying elements such as carbon, manganese, and silicon influence the severity of strain-ageing in low carbon steels.
   • High levels of carbon and manganese can exacerbate the strain-ageing effect in low carbon steels, leading to greater susceptibility to this phenomenon.

In summary, the phenomenon of strain-ageing is generally experienced with low carbon steel, particularly when it undergoes cold-working or plastic deformation followed by ageing at moderate temperatures. While high carbon steel and certain alloy steels may also exhibit strain-ageing, it is most commonly associated with low carbon steels.